1. Field of the Invention
This invention generally relates to a method for dynamically adjusting central processing unit (CPU) frequency, and more particularly to a power saving technology to dynamically adjusting CPU frequency.
2. Description of Related Art
As portable computer products prosper, including Personal Digital Assistant (PDA), notebook computer, etc., in addition to functionality of a computer its own, battery endurance is another significant consideration for users. Longer battery endurance brings longer travelling time for users when equipped equally.
Generally speaking, a CPU manufacturer assigns power supply category. Supposing ac power is supplied, CPU usage rate is adjusted to maximum upon efficiency. Yet if a battery is supplied, clocking and operating voltage are both properly reduced accordingly so as to prolong battery endurance. Therefore, in conventional art merely two modes are provided, that is ac power supply mode and battery power supply mode, which do not serve to adjust CPU clock according to CPU usage rate. Besides, the foregoing skill is merely for adjusting internal frequency of the CPU.
Among current Microsoft® operating system or other notebook computer manufacturers, power management is varied with different conditions, for example, power supply categories of desktop computers, notebook computers, etc., which is determined by battery power supply or external ac power supply. However, users need to manually select one of the conditions above under appropriate circumstances in order to comply with current power management mechanism.
MicroStar Technologies Inc. recently publicized a prompt CPU frequency adjustment method under Microsoft operating system, which is posted as patent number No. 511027. This technology provides a frequency selection unit that is displayed via window interface, so as to dynamically adjusting CPU clock and operation voltage. However, the frequencies are limited to what are selectively provided, and an additional core-cell chip has to be supplied, thus relevant routings are altered consequently.